Airplane propeller



' March 19; 1946.

J. E. BATHRAS AIRPLANE PROPELLER Filed Dec. 10, 1943 Man/55 5A7 7/7 25 5Inventor ttorneys FFICE AIRPLANE PROPELLER James E. Bathras, Portland,Maine Application December 10, 1943, Serial No. 513,760

1 Claim.

This invention relates to an airplane propeller,-

and particularly to the formation of the blades. thereof.

Airplane propellers are of relatively large size or have long blades,and they ordinarily create a loud humming noise when operating at highspeed. Also, with the ordinary airplane propeller, there is noticeableloss of efliciency at the tip portion of the blade, due to centrifugalslippage.

The primary objects of the present invention, therefore, are to providean airplane propeller which, through its particular blade formation.will be relatively quiet when operating at high speed, as well as highlyefiicient, and which will nullify tip loss resulting from centrifugalslippage, by causing a centripetal movement of air, through 9,particular arrangement and form of fin on the tip portion of the blade.

A specific object of the invention is to increase the efilciency of the-propeller.and bring about quiet operation through a particular finformation on the trailing edge of the blade, respectively along themajor intermediate portion of the trailing edge and on the trailing'edgeat the tip of the blade.

The present invention consists in the novel form, combination andarrangement of features and parts hereinafter more fully described,shown in the accompanying drawing and claimed.

in the drawing, wherein like reference characters indicate correspondingparts throughout the several views:

Figure 1 is a rear elevational view of an airplane propeller constructedin accordance with the present invention.

Figure 2 is a transverse section taken on the line 2-2 of Figure 1, and

Figure 3 is a section taken on line 8-8 of Figure 1.

Referring in detail to the drawing, I have shown an airplane propellerhaving two blades 5 of similar form and extending from opposite sides ofa central hub 8. Each blade has a pressure side 1 and a non-pressureside 8. The leading edge is indicated at 9, and the trailing edge atill. As usual, the blades are disposed at a desirable pitch or angle tothe axis of rotation, which may be on the line H. The direction ofrotation is indicated by the arrows l2 and the direction of air movementby the arrows It. The line I is the plane of rotation of the trailingedge and the line it the plane of rotation of the leading edge.

As shown clearly in Figure l, the leading edge 9 is substantiallyparallel to a line extending lon-. gitudinally of the blades and throughthe axis of rotation, while the trailing edge is bowed out considerablyto give sumcient blade area at the different sections. In accordancewith the present invention, a fin i8 is provided to extend along themajor intermediate portion of the trailing edge it, and this fin isturned outwardly and forwardly toward the direction of travel of theair-'- plane, as shown in Figure 2. Another smaller fin ii is providedon the trailing edge at the tip end portion of the blade, said fin I7being turned outwardly and rearwardly in the direction of air 20 tivelythick adjacent the nose or leading edge and tapers thinner toward thetrailing edge, but the cross sectional or airfoil shape of the blade mayvary to some extent. The effect of fin i8 is to lead the air from thepressure side outwardly and forwardly 'for gradually diminishingturbulence and thereby resulting in a considerable reducti n in the loudhumming noise ordinarily cause by an airplane propeller when operatingat high speed. The fin i'l causes acentripetal movement oi. air andthereby nullifies tip loss from centrifugal slippage.

Although a specific embodiment of the invention is illustrated anddescribed, it will be understood that various changes may be made withinthe scope of the invention as claimed.

What I claim as new is:

An airplane propeller adapted to berotated about an axis for displacingair and comprising a hub, a plurality of blades of similar formextending from the hub and disposed at an angle to the axis of rotation,each of said blades having an outwardly bowed trailing edge, a fincurved forwardly from the major intermediate portion oi.

the trailing edge oi each blade, and having an outwardly bowed trailingedge, and a second fin on the trailing edge at the tip end of eachblade, the lastnamed fin being curved rearwardly and having an outwardlybowed trailing edge.

JAMES 1:. names.

